Zigbee® Green Power (ZGP) is included in the Zigbee 3.0 specification (Z3) (Zigbee Alliance, Zigbee 3.0 specification, https://www.zigbee.org/zigbee-for-developers/greenpower/). It is an end-to-end open standard that allows ultra-low power devices called Green Power Devices (GPDs) to operate on Zigbee networks. The technology requires ultra-low power RF silicon that uses many orders of magnitude less power than required for a Zigbee sleepy or fully-networked wireless connection.
The EFR32xG22 EM2 and EM4 power modes along with the back-up RAM feature make it suitable to implement a periodic or event-based GPD sensor with bidirectional commissioning and secured key exchange.
There are two types of communication modes based on energy budget:
- Unidirectional: the device only transmits information to the Zigbee network
- Bidirectional: the device transmits and then receives information back, such as security material.
The bidirectional mode implementation uses EM2 power mode and the low energy sleep timer as a wake-up source between transmit and receive.
Commissioning and Security
The hardware acceleration in EFR32xG22 makes it possible to implement a GPD with the highest level of security (encryption and message integrity with application key exchange) during bidirectional commissioning.
Storage of Security Material
In a battery-backed GPD implementation, the back-up RAM can hold the security material during EM4 sleep.
The user guides on Green Power fundamentals and information about using the Silicon Labs Green Power framework can be found here: